~2140 families [doesn't sound right, as Crustacea alone have >1000, Myriapoda close to 200, Arachnida and Hexapoda close to a thousand each, too... =v=]

>1.3 million described species (plus many more undescribed)

Size

ranges from the smallest mite (about 0.10 mm) and the smallest insect (a Hymenopteran, Dicopomorpha echmepterygis at 0.139 mm), up to the King Crab (legspan more than 3.5 m), but most arthropods are in the range 2-25 mm

Identification

Three or more pairs of jointed legs (some mites have less, many insect larvae have none)

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